Parallels Desktop Flaw Allows Root Access on Macs; Intel Macs Cannot Install Fix

Root Privilege Escalation Discovered

JFrog's vulnerability research team, led by Yuval Moravchick, identified a flaw in Parallels Desktop for Mac, dubbed ParaShells. This vulnerability, tracked as CVE-2026-90894 with a CVSS score of 7.8, enables a local user without administrative privileges to execute arbitrary code with root access on the macOS system. The attack requires code already running on the machine as a normal user and does not function over a network.

Technical Details of the Exploit

The flaw resides in the prl_disp_service, a background service that runs as root to manage tasks like host networking and virtual machine package unpacking. JFrog found that the socket this service listens on was world-writable, allowing any program on the Mac to connect. The PrlSrv_LoginLocal call, which follows, only checks kernel-reported credentials for the connecting process, bypassing the need for a Parallels code signature or administrator account.

The exploit manipulates how the service constructs and parses the 'tar -xf "%1" -C "%2"' command used for unpacking virtual machine appliances. By inserting a double quote into the user-controlled folder name, an attacker can close the quoting early, allowing subsequent input to be interpreted as additional options for the root-privileged tar command. JFrog demonstrated this by using the '--use-compress-program' option to execute an arbitrary program as root, creating a passwordless sudo rule and opening a root shell.

Impact on Intel Mac Users

The fix for this vulnerability is included in Parallels Desktop 27. However, this version is not compatible with Intel-based Macs, leaving users of these machines exposed to the flaw. JFrog demonstrated the exploit on Parallels Desktop 26.4.0, build 57513, on an Apple silicon Mac, noting that a standard installation provides all necessary components for the attack, including the running service and a low-privileged local account.